Full-thickness dermal wounds often extend through the subcutaneous layer and are typically treated by packing the wound with dressing material to absorb wound exudate, reduce pain and prevent bacterial proliferation. Currently, such wound packings are retained in the wound by adhesive-backed tapes or films which are applied over the wound and adhesively secured to the skin surfaces surrounding the wound. When access to the wound is required for visual inspection, changing of the packing, or other reasons, the adhesive tape or film must be removed from the skin in order to expose the wound. Since many wounds require frequent visual inspection about every three to four hours and packings are often changed on average three times a day, the repeated stripping and application of an adhesive tape or covering to the wound site can cause significant skin irritation and even stripping of the skin.
In addition to the problems encountered with patient discomfort, the application of a new adhesive tape or covering every time the wound is inspected or the packing is changed is an extremely time-consuming process. The adhesive tape or covering must be carefully cut to size each time to ensure that the wound margins are avoided since application of adhesive to the wound itself could be intensely painful to the patient and detrimental to wound healing upon removal. The adhesive tape or covering must also be modified to be compatible with the location of the wound and accommodate for the curvature of the skin, skin folds, other wounds, other medical devices, etc. In addition, because adhesive-backed films, especially polyurethane dressings, are relatively expensive products, frequent changing and discarding of such dressings several times a day can be cost prohibitive.
Wound covers having a base portion which is secured to the skin surfaces surrounding a wound and having a reclosable cover are well known and examples of such devices are disclosed in U.S. Pat. Nos. 5,395,675, 4,795,435, 4,468,227 and RE. 29,319. However, it is believed that many of these constructions suffer from one or more shortcomings which make the devices less than effective in providing a reclosable wound cover which facilitates frequent opening and closing of the cover for frequent access to the wound. One such shortcoming lies in the fact that the upper layers of the base or the covers of such devices are generally larger than the adhesive which secures the device to the skin surfaces surrounding the wound. It is believed that repeated manipulation and opening and closing such large, and sometimes bulky, covers can adversely affect the adhesive attachment between the base and the skin surfaces surrounding the wound. Another shortcoming lies in the fact that many of such devices rely upon acrylic adhesives, either solely or in part, to adequately secure the device to the patient rather than more skin-friendly skin barrier materials.
An important aspect of this invention therefore lies in providing a reclosable wound cover which relies entirely on a skin barrier material for effective long-term attachment to the skin surfaces of the patient while still allowing for frequent opening and closing of the cover for inspection or access to the wound without affecting the attachment of the skin barrier material to the patient. The cover includes a planar, transparent cover film which permits visual inspection of the wound through an opening in the base. The cover also includes an adhesive border for releasably securing the cover to a backing layer of the base, and the cover film and backing layer of the base are formed of dissimilar materials so that the adhesive border has a greater affinity for remaining secured to the cover film than to the backing layer of the base. The cover is also smaller in outline than the base so that lifting forces applied to the cover will not tend to peel the larger base away from the skin surfaces of the patient and so that the cover, when it is re-closed, will always seal against the film of the base and not against the skin. The skin-friendly nature of the barrier layer allows the base to remain secured to the skin surfaces surrounding the wound for relatively long periods of time while the transparent cover allows for visual inspection and frequent access to the wound by opening and closing the cover.
Briefly, the reclosable wound cover of this invention comprises a base including a barrier layer of soft, conformable fluid-absorbing adhesive material and a thin, elastomeric backing layer covering a surface of the barrier layer opposite from its skin-contacting surface. The barrier layer and backing layer are coplanar and have a co-extensive perimeter so that the base is secured to the skin surfaces of the patient entirely by the barrier material. The wound cover also includes a reclosable cover having a planar, transparent cover film having a peripheral edge defining a perimeter smaller than the perimeter of the base. An adhesive border is secured along the peripheral edge of the cover film for releasably securing the cover to the backing layer of the base. The adhesive border has a greater affinity for remaining secured to the cover film than to the backing layer of the base so that the adhesive remains on the cover film during repeated opening and closing of the cover. Hinge means are secured along one end of the perimeter of the cover and to the backing layer for guiding the cover between an open position and a closed position in which the perimeter of the cover lies within the perimeter of the base and the adhesive border is secured to the backing layer of the base.
It is important that the perimeter of the cover is smaller than the perimeter of the base so that lifting forces applied to the cover will not tend to pull the larger barrier layer away from the surface of the skin and so that the cover does not extend beyond the base and contact the skin surfaces. Since the adhesive border will generally be composed of one type of adhesive, the cover film and the backing layer of the base are preferably composed of dissimilar materials so that the adhesive will have a greater affinity for remaining attached to the cover film than to the backing layer. In a preferred embodiment, the cover film is composed of polyurethane while the backing film is composed of a highly stretchable, gas and moisture vapor permeable polyetheramide, such as MEDIFILM sold by Bertek, Inc. of Saint Albans, Vt. Such a construction is believed to be particularly effective since the MEDIFILM adheres particularly tenaciously to the barrier material so that repeated opening and closing of the cover will not cause the backing film or layer to delaminate from the barrier material.
To further facilitate repeated opening and closing of the cover, the cover preferably includes at least one lift tab having a non-adhesive undersurface so that it will not adhere to the base. The user can readily lift and grip the tab to initiate and facilitate opening of the cover. The cover may also include tapered portions which extend from the opposite edges of the cover and converge towards the lift tab so that lifting forces exerted on the cover will be minimal at first and then will progressively increase as the tapered portions and cover are pulled back off of the base.
In one embodiment, the hinge means comprises a hinge composed of a layer of polymeric film having a layer of pressure-sensitive adhesive along its undersurface. The pressure-sensitive adhesive is preferably of moderate tack and is formulated to function in the presence of moisture. The hinge preferably extends along substantially one linear edge of the cover so that, during the reclosing operation, the hinge guides the cover back to a closed position within the perimeter of the base, thereby avoiding contact between the adhesive border of the cover and the skin surfaces of the patient.
In the preferred embodiment, the adhesive border takes the form of a peripheral strip of double-sided adhesive tape having first and second adhesive layers and a relatively non-stretchable substrate interposed between the adhesive layers. The substrate is preferably opaque and forms a visible frame about the peripheral edge of the cover film to visually assist the user in manipulating the transparent cover film. The increased thickness of the double-sided adhesive tape also physically assists the user in manipulating the thin cover film.
The base and cover of the wound cover may take the form of various shapes and sizes depending upon the particular application for which it is intended. In one alternate embodiment, the base and cover have a generally elongated, rectangular shape and the cover is provided with two lift tabs for facilitating repeated opening and closing of the cover.
Other objects, features and advantages of the present invention will become apparent from the specification and drawings.